Analysis of abnormal expression of G‐CSF gene in a novel tumor cell line (KHC 287) elaborating G‐CSF, IL‐1 and IL‐6 with co‐amplification of c‐myc and c‐ki‐ras

We established a human carcinoma cell line (KHC 287) from a patient with large‐cell‐type lung carcinoma associated with marked leukocytosis. The culture supernatant of KHC 287 cells promoted granulocytic colony formation of human bone‐marrow cells in semi‐solid culture. Colony formation was almost completely suppressed by treatment of the supernatant with a monoclonal anti‐granulocyte colony‐stimulating factor (G‐CSF) antibody. Not only G‐CSF but also interleukin‐la (IL‐1 a), IL‐Iβ and IL‐6 were detected in the culture supernatant by an ELISA method. Northern blot analysis of KHC 287 cells revealed distinct expression of these cvtokine genes. Southern blot hybridization of KHC 287 DNA snowed 20‐ and 40‐fold co‐amplification of c‐myc and c‐ki‐ras, respectively. The chloramphenicol acetyl transferase (CAT) activity was distinctly enhanced in the KHC 287 cells which were transfected with the 360 bp upstream region of G‐CSF gene inserted into pSVOOCAT, but not in non‐G‐CSF‐producing tumor cell lines. These results suggest that overproduction of the transactivating factor(s) which binds to the 360 bp of the G‐CSF upstream region is responsible for the abnormal expression of G‐CSF gene in KHC 287 cell line.